The present invention relates to a coating apparatus which rotates an object such as a semiconductor wafer to be coated, and coats a coating liquid to the surface thereof, and more particularly relates to a coating apparatus which can clean an inside of a container to which coating liquid dispersed by rotation of a spinner has been attached.
Conventionally, a resist rotary coating apparatus such as that shown in FIG. 17 has been used as a coating apparatus for rotating an object such as a semiconductor wafer to be coated and applying a coating thereon with a coating liquid. This coating apparatus is configured from a spin chuck 61 which is the rotation and holding means which holds a semiconductor wafer 60 horizontal and rotates it at high speed, a resist supply nozzle 62 which drops the coating liquid of resist liquid onto the semiconductor wafer 60, and an outer cup 63 and an inner cup 64 which form a container provided so as to enclose the semiconductor wafer 60 on the spin chuck 61.
The resist liquid which is dropped onto the semiconductor wafer 60 from the resist supply nozzle 62 is uniformly coated onto the semiconductor wafer 60 by the high-speed rotation of the spin chuck 61 and excess resist liquid is dispersed in the direction of the periphery of the semiconductor wafer 60 and attaches to the wall surfaces of the outer cup 63 and the inner cup 64. If the resist liquid which has attached to the wall surfaces of the outer cup 63 and the inner cup 64 stays there, then the resist will form a layer and dry. The dried resist liquid will then flake from the wall surfaces of the outer cup 63 and the inner cup 64 when there is an impact force or the like and will be dispersed as particles which will contaminate the semiconductor wafer 60 and lower the yield of wafers. Because of this, the outer cup 63 and the inner cup 64 are periodically removed and the substances attached to them are removed by washing. However, this washing operation takes a large amount of time and trouble.
With respect to this, this coating apparatus is provided with a washing mechanism which automatically removes the resist which has adhered to the outer cup 63 and the inner cup 64. More specifically, as shown in FIG. 17 and FIG. 18, the cups 63, 64 are formed with lead-in paths 65a, 65b which lead the washing liquid L which dissolves the resist, ring-shaped supply paths 66a, 66b for the distribution and supply of the washing liquid L which has been led in from the lead-in paths 65a, 65b to around the entire periphery of the cups 63, 64, and a plural number of small holes 67 for conducting the washing liquid L of the ring-shaped supply paths 66a, 66b to the surface to which the resist is attached. A washing liquid lead-in tube 69 is connected to the lead-in path 65 via a connector 68. Then, the washing liquid L which has been supplied to the ring-shaped supply paths 66a,66b passes through each of the small holes 67 and flows out over the entire outer peripheral surface of the inner cup 64 and the entire inner peripheral surface of the outer cup 63.
In addition, as shown in FIG. 19, there has been proposed a technology (See Japanese Patent Laid-Open Publication No. 184725-1983, Japanese Patent Laid-Open Publication No. 73630-1987) wherein a separate washing means has a dummy wafer 70 mounted on a spin chuck 61 and the washing liquid L is supplied to the dummy wafer 70 from a washing liquid supply nozzle 62 while the spin chuck 61 is being rotated at high speed.
In addition to this, technologies have also been disclosed for this type of washing apparatus, as for example in Japanese Patent Laid-Open Publication Nos. 211226-1984, 73629-1987, 41630-1988 and Japanese Utility Model Laid-Open Publication No. 25665-1989.
However, with the washing mechanisms in the coating apparatus described above, as shown in FIG. 17 and in FIG. 18, the structure of the outer cup 63 and the inner cup 64 becomes complex and expensive, as a consequence, and the processing and mounting are also difficult. In addition, the washing liquid L flows through hundreds of small holes 67 but since the washing liquid L flows more easily along paths in which it has flowed before, the washing liquid L does not flow uniformly across the entire surface of the outer cup 63 and inner cup 64, and there is therefore the problem of uneven washing. Furthermore, with this washing mechanism, the method is such that the washing liquid L flows a little at a time and dissolves the resist and so washing not only takes a long time, but there is also a high consumption of the washing liquid L. In addition, there is also the danger of various types of trouble such as the washing liquid L leaking from the connector 68. Furthermore, it is difficult to control the direction of dispersion of the washing liquid, and here is also the problem that the cup cannot be effectively cleaned.
In addition, with the latter apparatus, that is, the apparatus shown in FIG. 18, there is the possibility that the amount of washing liquid consumed can be reduced along with the time required for washing but the carrying in and out of the dummy wafer 70 takes time, and it is also necessary to manually take the standby spacer for the dummy wafer 70 in and out. Furthermore, there is also the problem that the particles, which have adhered to the surface of the dummy wafer 70, attach to the spin chuck 61 and contaminate the semiconductor wafer 60.